Description
Copier is a library and CLI app for rendering project templates. Prior to version 9.11.2, Copier suggests that it's safe to generate a project from a safe template, i.e. one that doesn't use unsafe features like custom Jinja extensions which would require passing the `--UNSAFE,--trust` flag. As it turns out, a safe template can currently write to arbitrary directories outside the destination path by using directory a symlink along with `_preserve_symlinks: true` and a generated directory structure whose rendered path is inside the symlinked directory. This way, a malicious template author can create a template that overwrites arbitrary files (according to the user's write permissions), e.g., to cause havoc. Version 9.11.2 patches the issue.
Problem types
CWE-61: UNIX Symbolic Link (Symlink) Following
Product status
References
github.com/...copier/security/advisories/GHSA-4fqp-r85r-hxqh
github.com/...ommit/b3a7b3772d17cf0e7a4481978188c9f536c8d8f6
github.com/copier-org/copier/releases/tag/v9.11.2